Identification of Drought Resistance in Wild Populations of Phaseolus vulgaris using an Ecological Genomic Approach

The ability to fully exploit wild Phaseolus vulgaris genetic diversity for improving drought and/or heat resistance in domesticated common bean is hindered by difficulties in phenotyping large number of individuals for these traits, precluding also the identification of useful molecular markers essential in breeding programs. In the current study, the integration of ecogeographical diversity analysis with high-throughput genotyping of wild P. vulgaris allowed the identification of putative drought-adapted populations in this species, along with relevant molecular markers associated with this stress. Analysis of spatial population structure identified five different populations in wild common beans, with three sub-populations in the Mesoamerican gene pool (MW1, MW2 and MW3), one population representative of the intermediate group from North Peru-Ecuador (PhI), and one population for the Andean gene pool (AW). These sub-populations showed significant differences regarding annual rainfall and annual Potential Evapo-Transpiration (PET), suggesting variability in drought adaptation within this species. Association analysis of genotypic data with variations in temperature, rainfall, and PET identified several genes significantly correlated with ecological variation in the wild populations analyzed. These genes are possibly involved in drought adaptation in wild P. vulgaris, and could constitute useful molecular markers for improving drought performance in domesticated common bean by introgression from wild populations.